Semiconductor components are mounted on a printed wiring board, usually on one side thereof. Cooling of such printed wiring boards with their associated semiconductor devices is required to keep the semiconductor devices below their critical temperature. The most common way of cooling such circuit card assemblies is by blowing air thereover. Of course, such air cooling has definite limits as to the amount of heat that can be removed, especially when the circuit card assembly is densely packed with electronic components or applied in an environment where direct external air impingement to the circuit card is undesirable or forbidden. Furthermore, such circuit card assemblies must be spaced so that adequate air can flow therebetween for cooling. Conductive cooling has been attempted by fitting of thermal mounting plates directly against the semiconductor device packages, usually between the component and the circuit card. Such thermal mounting plates are difficult to construct and often have poor thermal pathways due to long, thin thermal conductive sections. The thickness of the material is limited due to component lead lengths, and the thickness of the printed wiring board. Attempts to cool the semiconductor packages on the circuit card assembly by contact to the surfaces away from the printed wiring board have been unsuccessful due to the different sizes and heights of the packages. There is still need for a conduction cooling structure and method of making the structure by which a group of various sized electronic packaged devices assembled on a circuit card can be conductively cooled.
The uniqueness of this invention is that it provides a method for converting circuit card assemblies that were designed for direct air impingement convection cooling to one which will cool the electronics by means of conduction without redesigning the circuit card. It provides a removable, for repair, externally applied thermal mounting plate (conduction converter) that will cool the electronics conductively in a manner equal or superior to forced convection cooling. This represents significant saving of engineering labor required to redesign the circuit card.